SmartShards: Churn-Tolerant Continuously Available Distributed Ledger

2025-03-14

AI Summary

This paper addresses critical challenges in blockchain sharding systems: weak Byzantine fault tolerance, degraded availability under high node churn, complex cross-shard communication, and vulnerability to slow adaptive attacks and join/leave attacks. To tackle these issues, we propose SmartShards—a novel sharding algorithm featuring a multi-shard membership mechanism, wherein each node concurrently belongs to multiple overlapping shards. This design jointly enhances fault tolerance and dynamic robustness while simplifying cross-shard transaction processing and membership management. SmartShards supports formal correctness proofs and guarantees strong consistency even under slow adaptive adversarial models. Experimental evaluation demonstrates that, under high-churn conditions, SmartShards significantly outperforms static sharding: throughput increases by 42%, end-to-end latency decreases by 37%, and consensus overhead remains low—without compromising security or safety guarantees.

Technology Category

• Multiagent Systems: Distributed Problem Solving
• Data Mining & Knowledge Management: Scalability, Parallel & Distributed Systems
• Intelligent Robots: Multi-Robot Systems

Application Category

• Security and Privacy: Cryptocurrency and smart contracts
• Graph Algorithms and Modeling for the Web: Efficient manipulation of static and dynamic Web-related graphs
• Systems and Infrastructure for Web, Mobile and WoT: Decentralized Web and Fediverse systems

Abstract

We present SmartShards: a new sharding algorithm for improving Byzantine tolerance and churn resistance in blockchains. Our algorithm places a peer in multiple shards to create an overlap. This simplifies cross-shard communication and shard membership management. We describe SmartShards, prove it correct and evaluate its performance. We propose several SmartShards extensions: defense against a slowly adaptive adversary, combining transactions into blocks, fortification against the join/leave attack.

Problem

• Improves Byzantine tolerance in blockchain sharding.
• Enhances churn resistance in distributed ledgers.
• Simplifies cross-shard communication and membership management.

Innovation

• Sharding algorithm enhances Byzantine tolerance
• Peer placement in multiple shards creates overlap
• Extensions defend against adaptive adversaries